Report - Agence canadienne d'évaluation environnementale

Chapter 7 Impacts on the inhabited area
and human activities
Noise
Measuring noise and its effects on health
The sound level is adjusted to an average value, the equivalent sound level (Leq) for a
given time period, of either 1, 12, or 24 hours. It is measured in decibels A (dBA), a
logarithmic scale adapted to human sound perception. For the human ear, a change
would be perceptible starting at 3 dBA.
Chronic exposure to noise can bring on minor emotional symptoms, alterations in the
performance of daily tasks, and sleep disturbance 1 . A number of participants in the
public hearings made the point that the effects of environmental noise on health have
been scientifically documented and include an increase in cardiovascular disease,
temporary or permanent hearing loss, sleep disruption, learning problems, etc.
Criteria, guidelines and regulation
The World Health Organization suggests limiting noise within a home to less than
45 dBA to allow communication 2 . It also stipulates that maintaining sleep demands a
limit on noise of 30 dBA in the bedroom and less than 45 dBA outside the home
during the night. Finally, an outdoor sound level of 55 dBA, day or night, would
correspond to a strong disturbance while one of 50 dBA would be a moderate
disturbance.
The MDDEP applies criteria for the category of projects that corresponds to industrial
activities not subject to noise regulations during the construction and operation
phases. These criteria are different for the construction and operation periods and
presented below.
During construction, in the evening (7 p.m. to 10 p.m.) and the night (10 p.m. to
7 a.m.), any equivalent noise level over an hour (Leq 1 h) must be equal or inferior to
1. S.A. Stansfeld, “Noise, noise sensitivity and psychiatric disorder: Epidemiological and psychophysiological
studies”, Psychological Medicine - Monograph Supplement No. 22, 1992, p. 1-44.
2. On-line (April 30, 2007): www.who.int/docstore/peh/noise/bruit.htm].
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